Result: 
<%@ page import="sige.Usuario" %>
<%@ page import="java.io.File" %>
<!doctype html>
<html>
    <head>
        <meta name="layout" content="main">
        <g:set var="entityName" value="${message(code: 'usuario.label', default: 'Usuario')}" />
        <title><g:message code="default.show.label" args="[entityName]" /></title>
    </head>
    <body>
        <center>
          <h1><g:message code="default.show.label" args="[entityName]" /></h1>
        </center>
        <ul class="breadcrumb">
            <li>
                <a href="${createLink(uri: '/')}">
                  <i class="icon-home"></i>
                  <g:message code="default.home.label"/>
                </a>
                <span class="divider"> . </span>
            </li>
        </ul>
        <div id="show-usuario" class="content scaffold-show" role="main">
            
            <g:if test="${flash.message}">
              <div class="alert alert-info">
                <button type="button" class="close" data-dismiss="alert">&times;</button>
                ${flash.message}
              </div>
            </g:if>
            <div class="row span9 offset2">
                <div class="span2 well">   
                    <g:if test="${ (new File('images/usuarios/'+usuarioInstance?.id?.toString())).size() }">
                        <g:img dir="images/usuarios" file="${usuarioInstance?.id?.toString()}" 
                            contextPath="/" alt="Foto"/>
                    </g:if>
                    <g:else>
                        <g:img dir="images/usuarios" file="-1" 
                            contextPath="/" alt="Foto"/>
                    </g:else>
                </div>
                
                <div class="span5 well">
                    <g:if test="${usuarioInstance?.comoGostaDeSerChamado && usuarioInstance?.titulo}">
                        <b>${fieldValue(bean: usuarioInstance, field: "titulo")} </b>
                        ${fieldValue(bean: usuarioInstance, field: "comoGostaDeSerChamado")}
                    </g:if>
                    <g:else>
                        <b><g:message code="pessoa.nome.label" default="Nome"/> </b>
                        ${fieldValue(bean: usuarioInstance?.pessoa, field: "nome")}
                    </g:else>
                    <br/>
                    <b><g:message code="pessoa.email.label" default="Email"/> </b>
                    ${fieldValue(bean: usuarioInstance?.pessoa, field: "email")}
                </div>
            </div><!--/span8-->
        </div><!--/show-usuario-->
    </body>
</html>

